Aquarium calculators
Quick, free tools for the sums that come up when you keep a tank: how much salt to mix, what a reading means, and how much water you really have.
Saltwater mix calculator
Grams of salt for your RODI water, by brand, for the salinity you choose.
Salinity converter
Specific gravity, ppt and conductivity, corrected for temperature.
Alkalinity converter
ppm to dKH to meq/L.
Aquarium volume calculator
Real water volume from dimensions, minus rock and sand.
Water change calculator
How a reading falls after a water change, and how many it takes.